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(11) | EP 0 248 276 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Frequency standard using hydrogen maser |
(57) The invention provides a frequency standard, comprising: frequency-generating means (100) for generating electromagnetic energy at variable frequencies; a hydrogen maser (10) including means (12,13,19) to direct a stream of hydrogen atoms at a hyperfine energy state into a microwave cavity assembly (52) to generate electromagnetic energy at hydrogen resonance frequency; and an electronic means (120) to control the frequency of said frequency-generating means (100) to maintain a standard frequency with the electromagnetic energy generated by said hydrogen maser (10), said microwave cavity assembly (52) including a dielectric container defining by its outer surfaces a microwave cavity that is tuned to about hydrogen resonance frequency and including a discontinuous conductive coating on its outer surface in a predetermined configuration to suppress undesired oscillation of the microwave cavity. |